A battery charger having the ability to accommodate more than one battery at a time represents a significant convenience for the user. However, conventional multiple battery chargers often require additional circuitry capable of supplying the additional batteries. Such chargers can also pose a safety problem if current is supplied to the charging contacts even if a battery is not present. Finally, simultaneously charging multiple batteries can generate significant heat which also poses potential safety issues. Some prior art designs allow a user to manually select which battery is charged, but such chargers are subject to user error and at the least require additional effort by the user to operate the devices.
Accordingly, there is a need for a battery charger capable of accommodating multiple batteries which automatically supplies charging current to the desired battery. There is also a need for a multiple battery charger which minimizes heat build-up. This invention satisfies these and other needs.